For many years, the recording and playback of electrical signals has been accomplished with magnetic tape recorders, employing apparatus and techniques well known to the art. Although recording video signals, because of their larger bandwidth, requires more complex and expensive apparatus, video recording has been accomplished, also with apparatus and techniques well known in the art. The recording and playback of TV video signals has, for a number of reasons, advanced at a rapid rate, and indeed resulted in the appearance of consumer products which perform this function. With the advent of mass marketing, the high production rates for this apparatus has dramatically decreased the price of TV video recorders.
Video recorders in general, and the TV video recorders in particular, require a high effective tape speed to accept the wide video bandwidths. The earliest video recorders achieved high tape speed by merely running the tape drive at a sufficient velocity. The problem associated with such high tape speeds is that it requires vast amounts of tape for a given program material. The conventional TV video recorders employ apparatus in which the tape travels in one direction and the magnetic head is driven in another direction in order to achieve high relative velocities without requiring high tape velocity. Of course, the tape head must be regularly repositioned, but in TV video recording, the head repositioning is accomplished during frame retrace and thus no special precautions need be taken with the format of the video signal applied to the conventional video recorder.
Apparatus for recording other video signals, such as radar video signals, is associated with custom-made one-of-a-kind features with associated high costs. It is therefore one object of the present invention to provide apparatus which allows recording of radar video on conventional TV video recorders. It is another object of the present invention to provide apparatus to allow a radar video signal recorded on a conventional TV recorder to be played back and drive a conventional PPI display. It is another object of the present invention to provide a multiplexer, capable of accepting radar video data, signals definitive of azimuth and a 60 Hz. reference timing signal, to format the signals for recording on a conventional TV recorder. It is another object of the present invention to provide a demultiplexer for responding to signals played back from such a conventional TV recorder and reformatting the signals in order to drive a conventional PPI display.